Tracks changes to the utilization profile since the last checkpoint. This
is the "global" tracker for an environment that tracks changes as they
occur in live operations. Other "local" tracker classes are used to count
utilization locally and then later transfer the information to the global
tracker, this tracker.

All changes to this object occur must under the log write latch. It is
possible to read tracked info without holding the latch. This is done by
the cleaner when selecting a file and by the checkpointer when determining
what FileSummaryLNs need to be written. To read tracked info outside the
log write latch, call getTrackedFile or getTrackedFiles. activateCleaner
can also be called outside the latch.

Counts a node that has become obsolete and tracks the LSN offset, if
non-zero, to avoid a lookup during cleaning.

A zero LSN offset is used as a special value when obsolete offset
tracking is not desired. [#15365] The file header entry (at offset
zero) is never counted as obsolete, it is assumed to be obsolete by the
cleaner.

This method should only be called for LNs and INs (i.e, only for
nodes). If type is null we assume it is an LN.

Counts as countObsoleteNode does, tracks the obsolete LSN offset, but
does not fire an assert if the offset has already been counted. Use
this method when the same LSN offset may be counted twice in certain
circumstances.

This method should only be called for LNs and INs (i.e, only for
nodes). If type is null we assume it is an LN.